Polls back her up.
Fascinating that when Trump trumpets bald lies, he's viewed as refreshingly un-PC, but when Clinton speaks bold truths, she's pilloried for it.
A survey taken this May found that about two-thirds of Trump supporters believe Obama is a Muslim.
The same poll found 59 percent of Trump supporters believe Obama was not born in the United States.
PPP National Poll, May 69 2016
These views are incorrect but are also racist and xenophobic. They are rooted in the idea that a black man with an atypical name could not be a U.S.-born Christian but must be a secret Muslim born in Africa.
So when Hillary Clinton says half of Trump supporters hold bigoted views, she may be understating the issue. thinkprogress.org